Sensors are used in many fields of technology to measure certain physical quantities like temperature, pressure, light intensity, or magnetic fields—just to name a few examples.
Magnetic field sensors, for example, are used in various applications to sense a magnetic field. For example, in order to detect a position or movement a magnet may be mounted to a movable element like a pole wheel or a linear movable element. When the movable element moves, a magnetic field generated by the magnet varies, which may be detected by a magnetic field sensor. Such arrangements may, for example, be used to sense a position, velocity, a tampering of a magnetic field in smart meters or an acceleration. Sometimes, such arrangements and magnetic field sensors are employed in safety critical applications, for example, in the automotive field. In such applications, reliable operation of the magnetic field sensor is important. Furthermore, in such applications it may be desired that faults of the magnetic field sensor are detectable, such that a system where the magnetic field sensor is used may recognize a fault of the magnetic field sensor, for example. In conventional approaches, sometimes redundant magnetic field sensors are provided, for example, a main magnetic field sensor and a possibly smaller auxiliary magnetic field sensor. The main magnetic field sensor and the auxiliary magnetic field sensor may be provided on a same chip die. In other approaches, two separate sensor dies may be assembled in a single package. Outputs of the main and auxiliary magnetic field sensors may be compared, and if they differ by more than a predetermined threshold value, for example, this may indicate a fault condition.
The skilled person having benefit from the present disclosure will appreciate that not only magnetic field sensors but also sensors for other physical quantities may be used in such safety critical applications. Sometimes it may be desirable to combine even more sensors while keeping hardware complexity as low as possible.